The invention relates to a process of increasing the pozzolanic properties of a pozzolanic material, particularly fly ash from coal-fired units such as vessels of coal-fired power stations and whirling bed vessels and similar types of fly ash in order to increase the reactivity in relation to binding agents. By way of distinction binding agents can be divided into those reacting directly with fly ash such as calcium hydroxide containing substances and those reacting indirectly such as cements and unslaked limes.
Fly ashes are generally held to be pozzolanic i.e. in water they react with calcium hydroxide and subsequently harden.
Practice shows that such hardening proceeds very slowly and that there exist quite a few fly ashes that do not or hardly harden at all although such fly ashes do absorb a large quantity of calcium hydroxide.